Retort tube for furnaces



Jafl- 8, 1946- D. R. BABBITT ETAL '2,392,450

RETORT TUBE FOR FURNACES Filed Dec. 6, l1945 2 Sheets-Sheet 1 2 sheets-sheet 2 D.- R. BABBIT'r-ETAL BETORT TUBE FOR FURNACES Filed Deo. 6, 1945 Jan. 8, 1946.

Patented Jan. 8, 1946 RETORT TUBE FORFURNACES Daniel n. Babbitt and Edward T. Hewitt, san Francisco, Calif., assignors to Electric VSteel Foundry, Portland, Oreg., acorporation of Oregon application December c, 1943, serial No. 513,184' r (Cl. zee-19)- 3 Claims.

The present invention relates to retort tubes for furnaces, and is particularly concerned with retort tubes of the type comprising a lining of heat resistant tile, enclosed in a metal casing.

` One of the objects of the invention is the provision of an improved retort tube of the class described which is adapted to be used at extremely high temperatures and under a vacuum, and which is peculiarly adapted to permit the expansion which must take place in the metal casing without preventing the casing from performing its function of reenforcing and supporting the innertiles.

Another'object of the invention is the provision of an improved retort tube. adapted to withstand high temperatures simultaneously with the application of a high vacuum in the'interior of the retort tube, and in which provision is made for the expansion of the metal housing of the retort tube into spaces provided on the exterior of the tiles which the metal housing encloses. e

Another object of the invention is the provision of an improved retort tube which is adapted to have a longer life than the retorttubes of the prior art when subjected to temperatures of about 2100 F. and a vacuum of about 26 inches, as required in the manufacture of magnesium by the so-called Dolomite-Ferro Silicon" or Pidgeon Process. y

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there are 'f two sheets:

Fig. 1 is a vertical sectional View taken through a furnace equipped with retort tubes constructed according to the invention;

Fig. 2 is a fragmentary sectional view of the same furnace taken on a plane at right angles to that of Fig. 1;

Fig. 3 is a vertical sectional view taken on a plne passing through the axis of one of the retort u es;

Fig. 4 is a vertical sectional view taken on the plane of the line 4--4 of Fig. 3, looking in the direction of the arrows;

Fig. 5 is a larger fragmentary sectional view of the forward and open end of the retort tube shown in Fig. 3;

y Fig. 6 is a side elevational view of the retort constructed according to the invention and embodying a modified form of spiral grooves.

Referring to Figure 1, I0 indicates in its entirety, a furnace which is equipped with the improved retort tubes I I. The furnace is provided with the heat insulated base I2, front Wall I3, rear wall I4 and ceiling. I5.

The base I2 supports any suitable type of burners I5, the burners extending longitudinally of the retort tubes, and eachvretort tube is preferably supported upon a foundation I'I, in the form of any upwardly. extending wall carrying the supporting blocks i8 longitudinally spaced along its top. They retort tubes II are located side by side and spaced from each other `as, shown in Figure 2, with their open. ends I9 projecting from the forward wall I3 of the furnace.

Each retort tube preferably comprises an inner lining 2l), of heat resistive tile and an outer shell 2l of metal, adapted to withstand the high temperature, such as for example, a heat resisting steel.

The tile 2li, Whenassembled, form a cylindrical inner lining, and this lining maybe made up of blocks each of which is adapted to cover a predetermined area of the metal shell; for example, each block may comprise 1A of the circumference, or .1/6 or 1/8, or in some cases 1/2. Thus, as in Figure 4, four of the tile blocks make up the circumference of the lining.

, The tile. for the lining may be of uniform length so that a rplurality of tile sections may be used to make up a retort tube of any desired length.

Each tile is preferably formed so that when assembled they will provide the longitudinally extending grooves 22 between lining 20 and metal shell 2|. These grooves 22, may in some cases extend spirally as indicated 23 in Figure 6,

The metal shell 2l consists of a cylindrical tubular member of heat resistive steel, one end of which is closed by the end wall 24. The end wall may be provided with welded corners 25, its periphery, all of the parts of the metal shell 2| being welded together as; for example, by butt welding. At its open end the lining 20 is secured in the shell 2l by an annular heat resistive steel member 26, welded to the outer wall of the shell.

This annular member is also welded to an extension tube 21 comprising a relatively thick member of heat resistive steel which' may have a door supporting collar 28 at its outer end. A secondary shell 29 is secured to the collar 28 and the thick shell 2l, to provide an air insulated space 30 for insulating this end of the retort.

At the closed end of the retort the lining 20 may be provided with special end blocks 3l, suitably curved on the inside to provide a partially spherical end wall surface 32.

' 'I'.h'e heat insulating lining may be made of any refractory which is similar to that purchaseable on the open market under the trade-name of Zedf which is manufactured by Corhart Refractories Company of Louisville, Kentucky, The operation of the present retort structure is as follows: j f V l When the retort reaches the temperature of rabout 2100" F. th'e metal shell becomes very ductile. The vacuum of about 26 inches which must be maintained. during the present process'tends to cause metal shell to collapse. The metal shell is nevertheless impervious to air, andV its collapse .i

is prevented'by the lining of heat resistive tileV on the inside. These tile' form Ya reenforcinglining like the arch of an arch'way and they are adapted to withstand compression. As theV metal shell becomes heated to the temperature above mentioned, it expands, but this expansion mal7 be taken up by the metal shell moving down into the grooves 22 on the outside of the lining, since the shell is not supported against collapse at these grooves.

The depth of the grooves isV suchA that even when the shell is highly heated it is in close contact With'rits supporting tile lining, thereby preventing th'ecomplete collapse of the metal shell under vacuum. l.

The present construction is adapted to ,provide a retort with a much longer life than any retorts f of the prior art, thereby reducing the cost of the manufacture of magnesium by this process.

It will thusbe observed that we have invented- Y a new retort construction in which the h'eat resistive lining is adapted to withstand the com- V:1f

pression that is placed upon it by the outer metal to prevent collapse of the vmetal shell. vision has been made for the expansion of the metal shell into grooves located, on the outside of the h'eat insulating lining, and the metal shell is adapted to withstand and maintain the vacuum which is necessary for this process.

While we have illustrated and described a preferred embodiment of our invention, many modiiications may be made Without departing from.

the spirit of the invention and we do not wish to belimited to the exact construction shown, but desire to avail ourselves of all changes which are Ywithin therscope ofthefollowing claims.

Proy What we claim is new and desire to secure by United States Letters Patent, is:

l. In a retort tube for furnaces, adapted to withstand a high temperature and high vacuum, the combination of heat resistive refractory lining forming a substantially Icylindrical inner shell, with an Vouter metal shell-offheat resistive metal which.i'ssupported against collapse by the 'refractory"lining,4 said refractory lining being formed in itso'uter wall with recesses for receiving part of the metal shell when the metal shell expands to the temperaturesto which it is exposed, th'e said recesses comprising longitudinally extending curved grooves. f

l 2. In a, retort tubefor furnaces, adapted to withstand a high vtemperature andhigh vacuum, the combination of kheat resistive refractory lining forming a substantially cylindrical inner shell,

with an outer metal shell of heat resistive metal which is supported against collapse by 'the refractory lining, said refractory Vlining being formed in its Vouter wall with recesses for receiving part of th'e metal shell when Vthe metal shell expands to the temperatures to which it is exposed, the said recesses ycomprising spirallyV extending curved grooves. Y i 3. In a; retort tube for furnaces adapted to with-f stand a high temperature and high vacuum, the

combination of a .closed shell ofA thin heat'resistive sheet metal adaptedto provide aV fluidtight envelope for a retort, said', shell being collapsible at the elevated temperatures at which it is used, Witha heat resistiverefractory'lining of 'material of high compressive lstrength jand of` DANIELl R, BABBI'LT. EDWARD T. HEWIT'I. 

